Projectile



July 18, 1961 c. CRITCHFIELD EI'AL 2,992,612

PROJECTILE Filed July 14, 1944 FIG. 4. 22

BY JOHZ 5M0 6 MILLAR ORNEY United States Patent Ofiice 2,992,612Patented July 18, 1961 2,992,612 PROJECTILE Charles L. Critchfield,Chevy Chase, Md., and John McG. Mlllar, Utica, N.Y., assignors to theUnited States of America as represented by the Secretary of the NavyFiled July 14, 1944, Ser. No. 544,846 1 Claim. (Cl. 102-93) Thisinvention relates to projectiles for guns and more particularly to anovel sabot type of projectile especially adapted for attainingextremely high velocities when fired from a gun.

Generally the sabot type of projectile is a projectile having asubcaliber projectile core adapted for firing from a rifled gun. of fullcaliber. This is made possible by the use of a sabot of substantiallyfull caliber which acts as a bushing or spacer between the wall of thegun bore and the aforesaid projectile core. By employing a sabot,therefore, a subcaliber projectile core can be fired from a full calibergun, the higher pressures developed therein being used to produce highermuzzle velocities than would ordinarily be possible in a gun equal incaliber to the subcaliber projectile core. Immediately after clearingthe muzzle it is intended that the sabot be discarded to reduce airresistance.

In view of the foregoing it can be seen that this type of projectile hasadvantages which justify its use, but due to functional diflicultiesencountered in the past it has not been used extensively. 1

The sabot usually is made of a light material such as aluminum alloy orplastic which, due to its yieldability under centrifugal force, does notprovide proper axial centering means for the projectile core. Thisresults in the sabot projectile as a whole tending to yaw while stillwithin the gun bore as the projectile core becomes eccentric withrespect to the axis of the gun bore. Also, difliculty has beenencountered in the prompt discard of the sabot after it has cleared thegun. In certain types of projectiles the releasing of the sabot tends toupset the equilibrium of the projectile core causing it to veer from itscourse with the resulting possibility that it will miss the target.

One of the principal objects of the invention is to provide a sabotprojectile having means for maintaining a well centered fit of theprojectile core in a gun bore during movement therethrough.

A projectile made in accordance with the invention comp-rises a sabotincluding a base plug and a sleeve, both of a full caliber diameter, thebase plug abutting the after end of a subcaliber projectile core. Thesleeve tightly surrounds the subcaliber wall of the projectile core,leaving an ogive portion protruding therefrom in a forwardly direction.A camming ring is mounted in the front portion of the sleeve in aninternal annular recess which is tapered rearwardly. The camming ringhas an axial bore of a diameter substantially equal to that of theprojectile core to provide a centering means operable during setback.The peripheral wall of the camming ring is tapered to conform to thewall of the aforesaid recess. Longitudinally of the sleeve and insymmetrically spaced relationship are radial cuts, providing zones ofweakness to insure prompt discard of the sleeve. Radial cuts in thecamming ring are also provided to aid in its discard.

When the sabot projectile is fired from a gun, the pressure developed inthe powder chamber forces the projectile forwardly, the rifling in thegun bore engraving the turning band to produce a spinning of theprojectile. The force of setback resulting from acceleration of theprojectile causes the camming ring to shift rearwardly and, through thetapered surfaces, to expand the sleeve or skirt against the gun bore,thereby centering the projectile core in the gun bore and compensatingfor radial clearance and compressibility of the sabot. The projectilecore is thus centered in its travel through the gun bore. Upon clearingthe gun, the weakened zones or radial cuts allow the sabot and cammingring to break apart for discarding thereof under centrifugal force, thesymmetry and precision of the radial cuts providing for simultaneousrelease or breaking of all segments.

Another object of the invention is the provision of a sabot typeprojectilewhich is stable both before and after leaving the gun bore.

A still further object of the invention is the provision of a sabotprojectile which is of relatively simple construction and which ishighly efiicient functionally.

These and other objects will be better understood by reference to thedrawing and the following detailed description.

In the drawing:

FIG. 1 is a longitudinal sectional view of one form of the invention,some parts thereof being shown in elevation;

FIG. 2 is a longitudinal sectional view partly in elevation showing theprojectile in operation;

FIG. 3 is a transverse sectional View taken on line 3-3 of FIG. 1, and

FIG. 4 is a transverse sectional view taken along line 4-4 of FIG. 1.

Referring to the drawing, and more particularly to FIG. 1 thereof,numeral 10 indicates generally a sabot for a subcaliber projectile core:16. The core 16 has an externally uniform and uninterrupted surface,that is to say it is devoid of grooves and the like, making itparticularly adaptable to armor piercing. The sabot comprises a baseplug 11 and a sleeve 12 having an axial bore 13, the rear end of whichengages a shoulder 14 of the base plug 11. The shoulder 14 is formed bythe difference in size of the major and reduced portions of the baseplug, it being noted that the major portion substantially -fits the gunbarrel thus to receive the full impact of the powder gas. The engagementbetween the base plug and the sleeve at what delineates a recess 15 maybe a pressed fit, as shown, or the two elements may be threadedtogether. Occupying the bore 13 is the subcaliber projectile core 16which is securely held within the bore by either a forced fit orthreading. The sleeve 12, therefore, provides a coupling because of thetight fit that it has commonly on the base plug and core. The projectilecore 16 is cylindrical in shape over the greater part of its length withthe forward end portion terminating in an ogive 17. The ogive portion17, in assembly, protrudes beyond the forward end of the sleeve 12.

At the forward end portion of the sleeve 12 is an internal, taperedrecess 18, the diameter of which decreases as it extends rearwardly todefine a shoulder 19. Closely surrounding the cylindrical portion of theprojectile core 16 and in sliding engagement therewith is a camming ring20, the periphery 21 of which is tapered to correspond to the taper ofthe recess wall 18 which it engages.

Radially of the sleeve 12' and the camming ring 20 are symmetricallyspaced and longitudinally extending cuts 22 and 23 for providing zonesof weakness to facilitate the release of the sleeve.

A turning band 26 secured to the base plug 11 in any conventional mannerprovides means for rotating the projectile as it moves along the rifledgun bore.

The projectile par-ts normally assume the positions shown in FIG. 1. Inoperation, however, when the gun is tired, the projectile will moveforwardly in the gun bore (FIG. 2) and will be rotated by the action ofthe 3 rifling on turning band 26. The force of setback on the cam ring20, due to acceleration of the projectile, moves the cam ring rearwardlyand through the tapered surfaces '18, 21 expands the sleeve 12 intocontact with the wall of the gun barrel. In this way, axial centering ofthe projectile core 16 is maintained throughout the entire length of thegun banrel. When the sabot projectile emerges from the barrel, the sabotin its entirety is discarded, the sleeve 12 and ring 20 breaking apartunder centrifugal force. The discarding operation occurs immediatelyafter the projectile has cleared the gun, at which time the sleeve 12will be expanded to a point where it will be fractured along the radialcuts provided for such purpose. Inasmuch as the aforesaid radial cutsare positioned symmetrically and are uniformalily cut with respect todepth, all segments will be discarded together, eliminating thepossibility of disturbing the balance of the projectile. Upon discard ofthe sleeve 12, the base plug 11 will become detached from the projectilecore due to the greater air resistance on the plug. "0

We claim:

A missile comprising a subcaliber projectile as the core thereof, a fullcaliber tubular sabot providing a frictionally engaging sleeve aboutsaid core, said sabot be- 'ing slotted along substantially the axialextent thereof and to a depth Ll6SS than the radial extent of the sabotmaterial to substantially weaken said sabot to the action of centrifugalforces, said sabot being formed with an inner conical recess in theforward portion thereof, and a tapered camrning ring substantiallycomplementary to said conical recess slidably mounted on said corewithin said recess, firing of said missile from a rifled gun therebycausing said ring to cam the comically recessed portion of said sabotinto close engagement with the gun barrel, and the spin imparted by thebarrel causing the weakened sabot to disintegrate upon leaving thebarrel.

References Cited in the file of this patent UNITED STATES PATENTS132,903 Dana Nov. 12, 1872 2,382,152 Jakobsson Aug. 14, 1945 FOREIGNPATENTS 123,501 Great Britain Feb. 27, 1919 131,034 Great Britain Aug.21, 1919 46,057 Sweden Nov. 5, 1919 704,406' Germany Mar. 29, 1941

